我正在为我的WPF项目创建一个DataGridRadioButtonColumn。这是它的样子：
public class DataGridRadioButtonColumn : DataGridBoundColumn
{
private Dictionary<DataGridCell, RadioButton> _buttons = new Dictionary<DataGridCell, RadioButton>();
public string Group { get; set; }
public static readonly DependencyProperty GroupProperty = RadioButton.GroupNameProperty.AddOwner(
typeof(DataGridRadioButtonColumn), new FrameworkPropertyMetadata("DefaultGroup"));
protected override FrameworkElement GenerateElement(DataGridCell cell, object dataItem)
{
// Only generate the buttons once, to preserve the Group.
if (_buttons.ContainsKey(cell))
{
return (_buttons[cell]);
}
var radioButton = new RadioButton { GroupName = Group };
BindingOperations.SetBinding(radioButton, ToggleButton.IsCheckedProperty, Binding);
_buttons.Add(cell, radioButton);
return radioButton;
}
protected override FrameworkElement GenerateEditingElement(DataGridCell cell, object dataItem)
{
// Use the same one we generated before.
return _buttons[cell];
}
protected override object PrepareCellForEdit(FrameworkElement editingElement, RoutedEventArgs editingEventArgs)
{
var radioButton = editingElement as RadioButton;
if (radioButton == null) return null;
return radioButton.IsChecked;
}
}
这是一个使用它的例子：
<local:DataGridRadioButtonColumn
Width="0.33*"
Binding="{Binding PrimaryChecked, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
Group="Group1"
Header="PRI" />
一切都按照我的预期运作，包括单击单选按钮“取消选中”最初选择的单选按钮。此取消选中依赖于Group依赖项属性。
我唯一的问题是未选中的单选按钮不会在网格中注册为行编辑。只有我单击的单选按钮才会注册行编辑，并且为了正确保存数据，必须保存两行（包含我单击的单选按钮的行和包含未选中的单选按钮的行）。
如何告诉未选中单选按钮的数据行是否已编辑，以便正确更新DataGrid绑定集合中的匹配元组？
请注意，我在每行中使用的模型中实现了IEditableObject接口，因此它并不像仅仅依赖INotifyPropertyChanged那么简单。它确实需要在DataGrid Row中触发BeginEdit()。我不认为程序清除单选按钮无论如何都会触发PropertyChanged，因为更改不会反映在底层的Model对象中。
根据要求，这是一个MCVE（或者一个更好的部分，无论如何）：
<Application x:Class="WpfApp11.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApp11"
StartupUri="MainWindow.xaml">
<Application.Resources>
</Application.Resources>
</Application>
<Window
x:Class="WpfApp11.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:WpfApp11"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
Title="MainWindow"
Width="800"
Height="450"
mc:Ignorable="d">
<Grid>
<DataGrid ItemsSource="{Binding Items, UpdateSourceTrigger=PropertyChanged}">
<DataGrid.Columns>
<DataGridTextColumn
Width="0.7*"
Binding="{Binding Path=Name, Mode=TwoWay}"
Header="Name" />
<local:DataGridRadioButtonColumn
Width="0.3*"
Binding="{Binding PrimaryChecked, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
Group="Group1"
Header="PRI" />
</DataGrid.Columns>
</DataGrid>
</Grid>
</Window>
using PropertyChanged; //Fody
namespace WpfApp11
{
[AddINotifyPropertyChangedInterface] // PropertyChanged.Fody
public class Model
{
public string Name { get; set; }
public bool? PrimaryChecked
{
get;
set;
}
}
}
using System.Collections.ObjectModel;
using PropertyChanged; // Fody
namespace WpfApp11
{
[AddINotifyPropertyChangedInterface] // PropertyChanged.Fody
public class ViewModel
{
public ViewModel()
{
Items = new ObservableCollection<Model>
{
new Model {Name = "George"},
new Model {Name = "Fred"},
new Model {Name = "Tom"},
};
}
public ObservableCollection<Model> Items { get; set; }
}
}
如您所见，此代码不起眼。
这是有趣的地方。让我们在模型上放置一个IEditableObject实现。 IEditableObject被DataGrid认可;它允许您为每个数据行提供更改跟踪和撤消功能等内容：
public class Model : EditableValidatableObject<Model>
{
public string Name { get; set; }
public bool? PrimaryChecked
{
get;
set;
}
}
using PropertyChanged;
using System;
using System.ComponentModel;
namespace WpfApp11
{
/// <summary>
/// Provides an implementation of the IEditableObject and INotifyDataErrorInfo interfaces for data transfer objects.
/// </summary><remarks>
/// The IEditableObject interface is typically used to capture the BeginEdit, EndEdit, and CancelEdit semantics of a DataRowView.
/// Making something an IEditableObject enables full editing and undo capabilities in a DataGrid.
///
/// The INotifyDataErrorInfo implementation uses Validation Attributes to validate the values of properties on the DTO.
/// This information is used to indicate that a value entered by the user is invalid.
///
/// See T_Asset.cs and T_TestPoint.cs for usage examples.
/// </remarks>
[AddINotifyPropertyChangedInterface]
public abstract class EditableValidatableObject<T> : AnnotationValidationViewModel, IEditableObject
{
/// <summary>
/// Constructor, sets up the INotifyDataErrorInfo implementation.
/// </summary>
private T Cache { get; set; }
private object CurrentModel { get { return this; } }
public RelayCommand CancelEditCommand
{
get { return new RelayCommand(CancelEdit); }
}
private bool IsDirty
{
get
{
if (Cache == null) return false;
foreach (var info in CurrentModel.GetType().GetProperties())
{
if (!info.CanRead || !info.CanWrite)
continue;
var oldValue = info.GetValue(Cache, null);
var currentValue = info.GetValue(CurrentModel, null);
if (oldValue == null && currentValue != null)
return true;
if (oldValue != null && !oldValue.Equals(currentValue))
return true;
}
return false;
}
}
#region IEditableObject Implementation
public bool Added { get; set; }
public bool Edited { get; set; }
public bool Deleted { get; set; }
public void BeginEdit()
{
Cache = Activator.CreateInstance<T>();
var type = CurrentModel.GetType();
//Set Properties of Cache
foreach (var info in type.GetProperties())
{
if (!info.CanRead || !info.CanWrite) continue;
var oldValue = info.GetValue(CurrentModel, null);
Cache.GetType().GetProperty(info.Name).SetValue(Cache, oldValue, null);
}
if (!Added && !Deleted && IsDirty)
{
Edited = true;
}
}
public virtual void EndEdit()
{
if (!Added && !Deleted && IsDirty)
{
Edited = true;
}
Cache = default(T);
}
public void CancelEdit()
{
if (Cache == null) return;
foreach (var info in CurrentModel.GetType().GetProperties())
{
if (!info.CanRead || !info.CanWrite) continue;
var oldValue = info.GetValue(Cache, null);
CurrentModel.GetType().GetProperty(info.Name).SetValue(CurrentModel, oldValue, null);
}
}
#endregion
}
}
AnnotationValidationViewModel不起眼;它只是INotifyDataErrorInfo的一个实现，它使用数据注释进行验证。
上面的IEditableObject实现的关键部分是BeginEdit()方法，数据网格行使用该方法来指示编辑已经发生的基础模型。单击单选按钮时会调用此方法，但在自动取消选中其他单选按钮时则不会调用此方法。
由于BeginEdit()永远不会在未检查的行上调用，因此Edited属性永远不会被设置。我依靠Edited属性来知道我需要将哪些记录保存回数据库。
在考虑之后，我决定对我的DataGridRadioButtonColumn实现进行一些更改。它现在看起来像这样：
public class DataGridRadioButtonColumn : DataGridBoundColumn
{
private Dictionary<DataGridCell, RadioButton> _buttons = new Dictionary<DataGridCell, RadioButton>();
private Dictionary<RadioButton, dynamic> _models = new Dictionary<RadioButton, dynamic>();
public string Group { get; set; }
public static readonly DependencyProperty GroupProperty = RadioButton.GroupNameProperty.AddOwner(
typeof(DataGridRadioButtonColumn), new FrameworkPropertyMetadata("Group1"));
protected override FrameworkElement GenerateElement(DataGridCell cell, object dataItem)
{
if (_buttons.ContainsKey(cell))
{
return (_buttons[cell]);
}
var radioButton = new RadioButton { GroupName = Group };
radioButton.Unchecked += RadioButton_Unchecked;
BindingOperations.SetBinding(radioButton, ToggleButton.IsCheckedProperty, Binding);
_buttons.Add(cell, radioButton);
_models.Add(radioButton, dataItem);
return radioButton;
}
private void RadioButton_Unchecked(object sender, RoutedEventArgs e)
{
var button = sender as RadioButton;
dynamic model = _models[button];
try
{
model.Edited = true;
}
catch { }
}
protected override FrameworkElement GenerateEditingElement(DataGridCell cell, object dataItem)
{
return _buttons[cell];
}
protected override object PrepareCellForEdit(FrameworkElement editingElement, RoutedEventArgs editingEventArgs)
{
var radioButton = editingElement as RadioButton;
if (radioButton == null) return null;
return radioButton.IsChecked;
}
}
这是它的工作原理。我添加了一个字典，捕获每个单选按钮的模型，当创建一个单选按钮时，我将模型添加到新字典并挂钩单元格上的Unchecked事件：
protected override FrameworkElement GenerateElement(DataGridCell cell, object dataItem)
{
if (_buttons.ContainsKey(cell))
{
return (_buttons[cell]);
}
var radioButton = new RadioButton { GroupName = Group };
radioButton.Unchecked += RadioButton_Unchecked; // Added
BindingOperations.SetBinding(radioButton, ToggleButton.IsCheckedProperty, Binding);
_buttons.Add(cell, radioButton);
_models.Add(radioButton, dataItem); // Added
return radioButton;
}
然后，我只是在事件触发时在模型中设置Edited属性：
private void RadioButton_Unchecked(object sender, RoutedEventArgs e)
{
var button = sender as RadioButton;
dynamic model = _models[button];
try
{
// Notify IEditableObject implementation, if it exists.
model.Edited = true;
}
catch { }
}